Assessment of polystyrene nano plastics effect on human salivary α-amylase structural alteration: Insights from an in vitro and in silico study.

The study found that the enzyme activity of human salivary α-amylase (α-AHS) was competitively inhibited by nanoplastic polystyrene (PS-NPs), with a half-inhibitory concentration (IC50) of 92 µg/mL, while the maximum reaction rate (Vmax) remained unchanged at 909 µg/mL•min. An increase in the concentration of PS-NPs led to a quenching of α-AHS fluorescence with a slight red shift, indicating a static mechanism. The binding constant (Ka) and quenching constant (Kq) were calculated to be 2.92 × 1011 M-1 and 1.078 × 1019 M-1• S-1 respectively, with a hill coefficient (n) close to one and an apparent binding equilibrium constant (KA) of 1.54 × 1011 M-1. Molecular docking results suggested that the interaction between α-AHS and PS-NPs involved π-anion interactions between the active site Asp197, Asp300 residues, and van der Waals force interactions affecting the Tyr, Trp, and other residues. Fourier transform infrared (FT-IR) and circular dichroism (CD) analyses revealed conformational changes in α-AHS, including a loss of secondary structure α-helix and ß-sheet. The study concludes that the interaction between α-AHS and PS-NPs leads to structural and functional changes in α-AHS, potentially impacting human health. This research provides a foundation for further toxicological analysis of MPs/NPs in the human digestive system.

Assessment on interactive prospectives of nanoplastics with plasma proteins and the toxicological impacts of virgin, coronated and environmentally released-nanoplastics.

Recently, the concerns about micro- and nano-plastics (NPs) toxicity have been increasing constantly, however the investigations are quiet meager. The present study provides evidences on the toxicological prospectives of virgin-, coronated- and isolated-NPs on human blood cells and Allium cepa root tip, respectively. Several plasma proteins displayed strong affinity towards NPs and produced multi-layered corona of 13 nm to 600 nm size. The coronated-NPs often attracted each other via non-specific protein-protein attraction which subsequently induced protein-induced coalescence in NPs. In the protein point of view, the interaction caused conformational changes and denaturation of protein thereby turned it as bio-incompatible. The coronated-NPs with increased protein confirmation changes caused higher genotoxic and cytotoxic effect in human blood cells than the virgin-NPs. On the other hand, virgin-NPs and the NPs isolated from facial scrubs hindered the root growth and caused chromosome aberration (ring formation, C-mitotic and chromosomal breaks, etc.) in root of Allium cepa. At the outset, the present study highlights the urgent need of scrutinization and regulation of NPs use in medical applications and pre-requisition of additional studies for assessing the bio-accumulation and bio-magnification of NPs.

Toxicity assessment of zero valent iron nanoparticles on Artemia salina.

The present study deals with the toxicity assessment of two differently synthesized zero valent iron nanoparticles (nZVI, chemical and biological) as well as Fe2+ ions on Artemia salina at three different initial concentrations of 1, 10, and 100 mg/L of these particles. The assessment was done till 96 h at time intervals of 24 h. EC50 value was calculated to evaluate the 50% mortality of Artemia salina at all exposure time durations. Between chemically and biologically synthesized nZVI nanoparticles, insignificant differences in the level of mortality were demonstrated. At even 24 h, Fe2+ ion imparted complete lethality at the highest exposure concentration (100 mg/L). To understand intracellular oxidative stress because of zero valent iron nanoparticles, ROS estimation, SOD activity, GSH activity, and catalase activity was performed which demonstrated that ionic form of iron is quite lethal at high concentrations as compared with the same concentration of nZVI exposure. Lower concentrations of nZVI were more toxic as compared with the ionic form and was in order of CS-nZVI > BS-nZVI > Fe2+ . Cell membrane damage and bio-uptake of nanoparticles were also evaluated for all three concentrations of BS-nZVI, CS-nZVI, and Fe2+ using adult Artemia salina in marine water; both of which supported the observations made in toxicity assessment. This study can be further explored to exploit Artemia salina as a model organism and a biomarker in an nZVI prone aquatic system to detect toxic levels of these nanoparticles. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1617-1627, 2017.

Stability assessment of hydro dispersive nanometric permethrin and its biosafety study towards the beneficial bacterial isolate from paddy rhizome.

Nanopesticides such as nanopermethrin can serve as an alternative to conventional pesticides causing eco-toxicity. The nanoformulation of this pyrethroid pesticide was carried out by solvent evaporation of pesticide-loaded microemulsion. The Z average for the nanopermethrin dispersion in paddy field water was found to be 169.2 ± 0.75 nm with a polydispersity index of 0.371 that exhibits uniform dispersion. Further, the nanopermethrin (NP) dispersion exhibited an effective stability in the paddy field water for a duration of 48 h with a Z average of 177.3 ± 1.2 nm and a zeta potential of -30.7 ± 0.9 mV. The LC50 of the nanopermethrin against Culex tritaeniorhynchus in the field condition was found to be 0.051 µg/mL. In addition to the stability assessment, the biosafety of the nanopermethrin was commenced on the beneficial bacterial isolate Enterobacter ludwigii (VITSPR1) considered as plant growth-promoting rhizobacteria. The toxic effect of nanopesticide was compared to its bulk counterpart, i.e. bulk permethrin (BP) at a concentration of 100 µg/mL, and the nanopesticide was found to be potentially safe. The results of biomarker enzymatic assays (lipid peroxidase, glutathione reductase, lactate dehydrogenase) displayed insignificant (p < 0.05) toxicity of NP towards the bacterial cells compared to BP. The live-dead cell staining and SEM analysis illustrated negligible toxicity of NP towards the bacteria. The non-toxic behaviour of the NP towards the non-target species was studied which displayed the eco-safe property of NP.

A comparative study with biologically and chemically synthesized nZVI: applications in Cr (VI) removal and ecotoxicity assessment using indigenous microorganisms from chromium-contaminated site.

In the present communication, we report a comparative study of Cr (VI) removal using biologically synthesized nano zero valent iron (BS-nZVI) and chemically synthesized nZVI (CS-nZVI), both immobilized in calcium alginate beads. The parameters like initial Cr (VI) concentration, nZVI concentration, and the contact time for Cr (VI) removal were optimized based on Box-Behnken design (BBD) by response surface modeling at a constant pH 7. Under the optimized conditions (concentration of nZVI = 1000 mg L(-1), contact time = ∼ 80 min, and initial concentration of Cr (VI) = 10 mg L(-1)), the Cr (VI) removal by the immobilized BS-nZVI and CS-nZVI alginate beads was 80.04 and 81.08 %, respectively. The adsorption of Cr (VI) onto the surface of alginate beads was confirmed by scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) analysis. The applicability of the process using both the sorbents was successfully test medium Cr (VI) spiked environmental water samples. In order to assess the ecotoxic effects of nZVI, the decline in cell viability, generation of intracellular reactive oxygen species (ROS), cell membrane damage, and biouptake was studied at 1000 mg L(-1) concentration, with five indigenous bacterial isolates from chromium-contaminated lake sediments and their consortium.

Antibacterial activity of neem nanoemulsion and its toxicity assessment on human lymphocytes in vitro.

Neem (Azadirachta indica) is recognized as a medicinal plant well known for its antibacterial, antimalarial, antiviral, and antifungal properties. Neem nanoemulsion (NE) (O/W) is formulated using neem oil, Tween 20, and water by high-energy ultrasonication. The formulated neem NE showed antibacterial activity against the bacterial pathogen Vibrio vulnificus by disrupting the integrity of the bacterial cell membrane. Despite the use of neem NE in various biomedical applications, the toxicity studies on human cells are still lacking. The neem NE showed a decrease in cellular viability in human lymphocytes after 24 hours of exposure. The neem NE at lower concentration (0.7-1 mg/mL) is found to be nontoxic while it is toxic at higher concentrations (1.2-2 mg/mL). The oxidative stress induced by the neem NE is evidenced by the depletion of catalase, SOD, and GSH levels in human lymphocytes. Neem NE showed a significant increase in DNA damage when compared to control in human lymphocytes (P<0.05). The NE is an effective antibacterial agent against the bacterial pathogen V. vulnificus, and it was found to be nontoxic at lower concentrations to human lymphocytes.

In vivo genotoxicity assessment of titanium dioxide nanoparticles by Allium cepa root tip assay at high exposure concentrations.

The industrial production and commercial applications of titanium dioxide nanoparticles have increased considerably in recent times, which has increased the probability of environmental contamination with these agents and their adverse effects on living systems. This study was designed to assess the genotoxicity potential of TiO2 NPs at high exposure concentrations, its bio-uptake, and the oxidative stress it generated, a recognised cause of genotoxicity. Allium cepa root tips were treated with TiO2 NP dispersions at four different concentrations (12.5, 25, 50, 100 µg/mL). A dose dependant decrease in the mitotic index (69 to 21) and an increase in the number of distinctive chromosomal aberrations were observed. Optical, fluorescence and confocal laser scanning microscopy revealed chromosomal aberrations, including chromosomal breaks and sticky, multipolar, and laggard chromosomes, and micronucleus formation. The chromosomal aberrations and DNA damage were also validated by the comet assay. The bio-uptake of TiO2 in particulate form was the key cause of reactive oxygen species generation, which in turn was probably the cause of the DNA aberrations and genotoxicity observed in this study.